1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate.
2. Description of the Background Art
In photolithographic processes in manufacturing processes of semiconductor devices, liquid crystal displays, and so on, resist films are first formed on substrates. The resist films formed on the substrates are exposed in predetermined patterns. The substrates that have been subjected to exposure processing, as described above, are then subjected to development processing, so that resist patterns are formed on the substrates.
Generally, widely used as methods of forming the resist films on the substrates has been spin coating.
A device for forming a film by the spin coating (hereinafter referred to as a coating device) mainly comprises a processing cup arranged so as to surround a substrate and a processing unit arranged so as to surround the processing cup (see JP 2000-24575 A, for example).
In such a coating device, clean air whose temperature and humidity are controlled is introduced by a fan or the like from above the processing unit, to control an atmosphere around the substrate, and is forcedly exhausted from the bottom thereof, to forcedly exhaust the atmosphere around the substrate.
In order to maintain a temperature and humidity suitable for processing in the coating device, a sufficient amount of air is supplied toward the substrate from above the substrate by an air control unit (ACU).
When the supplied air flows from the center of the substrate to a peripheral edge thereof and is exhausted from the bottom of the processing cup, however, turbulent flow is generated by friction between the flow of the air and an air current generated by the rotation of the substrate at the peripheral edge of the substrate.
As a result, particles adhering on an inner surface or the like of the processing cup and mists of a resist liquid floating in the processing cup are scattered by the generated turbulent flow. This may, in some cases, cause the scattered particles to adhere on the substrate. As a result, processing defects occur in the substrate.